OsSQD1 at the crossroads of phosphate and sulfur metabolism affects plant morphology and lipid composition in response to phosphate deprivation

Abstract

In phosphate (Pi)‐deprived Arabidopsis (Arabidopsis thaliana), phosphatidylglycerol (PG) is substituted by sulfolipid for maintaining Pi homeostasis. Sulfoquinovosyl diacylglycerol1 (AtSQD1) encodes a protein, which catalyzes uridine diphosphate glucose (UDPG) and sulfite (SO32−) to UDP‐sulfoquinovose, which is a key component in the sulfolipid biosynthetic pathway. In this study, a reverse genetics approach was employed to decipher the function of the AtSQD1 homolog OsSQD1 in rice. Differential expressions of OsSQD1 in different tissue and response to −P and −S also detected, respectively. The in vitro protein assay and analysis suggests that OsSQD1 is a UDP‐sulfoquinovose synthase. Transient expression analysis showed that OsSQD1 is located in the chloroplast. The analyses of the knockout (ossqd1) and knockdown (Ri1 and Ri2) mutants demonstrated reductions in Pi and total P concentrations, 32Pi uptake rate, expression levels of Pi transporters and altered developmental responses of root traits, which were accentuated during Pi deficiency. The inhibitory effects of the OsSQD1 mutation were also evident in the development of reproductive tissue. Furthermore, OsSQD1 differently affects lipid composition under different Pi regime affects sulfur (S) homeostasis. Together, the study revealed that OsSQD1 affects Pi and S homeostasis, and lipid composition in response to Pi deprivation.

Transcriptomic analysis at organ and time scale reveals gene regulatory networks controlling the sulfate starvation response of Solanum lycopersicum

“…4c and Table S5), suggesting that sulfate deficiency also affects internal phosphate levels in tomato plants. Specifically, we found 52 genes in this biological process including SPX genes [70], phosphatases and genes encoding enzymes involved in phosphate mobilization by membrane lipid remodeling such as UDP-sulfoquinovose synthase [71,72] (Figure S4). In order to determine the response of this set of phosphate-related genes to sulfate starvation in tomato plants, we computed the average fold of change between sulfate starved and control samples in both tissues and we then performed a hierarchical clustering analysis.…”

Transcriptomic analysis at organ and time scale reveals gene regulatory networks controlling the sulfate starvation response of Solanum lycopersicum.

“…The most over-represented biological process in this group of genes was "cellular response to phosphate starvation" suggesting that sulfate de ciency also affects internal phosphate levels in tomato plants. Speci cally, we found 52 genes in this biological process including SPX genes [35], phosphatases and those encoding enzymes involved in phosphate mobilization by membrane lipid remodeling such as sulfoquinovosyl-diacylglycerol [36,37] (Figure S5). In order to verify the response of this set of genes to sulfate starvation in tomato plants, we computed the average fold of change between sulfate starved and control samples in both tissues and we then performed a hierarchical clustering analysis.…”

Transcriptomic analysis at organ and time scale reveals gene regulatory networks controlling the sulfate starvation response of Solanum lycopersicum.

“…4C and Table S5), suggesting that sulfate de ciency also affects internal phosphate levels in tomato plants. Speci cally, we found 52 genes in this biological process including SPX genes [69], phosphatases and genes encoding enzymes involved in phosphate mobilization by membrane lipid remodeling such as UDP-sulfoquinovose synthase [70,71] ( Figure S4). In order to determine the response of this set of phosphate-related genes to sulfate starvation in tomato plants, we computed the average fold of change between sulfate starved and control samples in both tissues and we then performed a hierarchical clustering analysis.…”